Steel T-posts are often used to support fence such as woven or barbed wire in agricultural applications. In some cases, steel T-posts may be used to support other types of fence, e.g. landscape or privacy fence. Usually, the T-posts are hand-driven into the ground with a weighted steel sleeve, closed on one end and acting as a slide hammer. The result is a low-cost, easily-installed support for fence. Height of a T-post above the ground after being driven into place is typically about 5 ft (1.5 m) in agricultural applications for the control of livestock.
As rural construction on small acreage plots has increased, wild deer have proliferated due to fewer natural predators and hunting restrictions. These deer become emboldened and in many areas are a nuisance, as they eat and otherwise destroy vegetable gardens and plants near residences. Deer can easily jump over the typical agricultural fence. This specification discloses a T-post extender that, when used in combination with a T-post, increases the effective post height. By this means, the height of existing fence can be increased, and new high fence using T-posts and T-post extenders as fence supports can be constructed.
Prior Art
There is more than one prior art fence method to control deer. One method uses two parallel fences spaced a few feet apart, neither being particularly high. Deer do not like to jump one fence and land on another and so will be controlled by the parallel fence arrangement.
Another prior art method places a high voltage electric wire parallel to and outside an existing agricultural fence. Deer coming within jumping range of the agricultural fence will brush against the electric wire and not jump the fence. An electric fence by itself is usually not sufficient because deer will often run right through and destroy it, thereby requiring it to be periodically maintained.
Another prior art method uses a footing obstacle outside an existing fence. For example, the footing obstacle could be slatted wood pallets laid on the ground outside the fence. Deer avoid the pallets because their feet slip between the slats.
These prior art methods waste the real estate between the parallel fences in the first case, between the electric wire and fence in the second case, and over the width of the footing obstacle in the third case. The extra material cost can be significant where parallel fences or a footing obstacle is used. If the high voltage electric wire method is used, there is added cost and maintenance required to ensure that power is applied.
The most obvious prior art method increases the height of the fence to a level that prevents deer from jumping over. This is accomplished by using posts of a sufficient length to support the higher fence. T-posts of length 10 ft (3.05 m) are available for this. While some of this length will be in the ground, a fence height of 8 ft (2.44 m) can be achieved, and that will control deer in most circumstances. Alternatively, long wood or concrete posts may be used.
Further Discussion of Prior Art Using Long Posts
Although long T-posts can be purchased to support fence high enough to control deer, they are costly, and it is difficult to drive them without a ladder or something to stand on. Other types of posts, such as wood or concrete posts of sufficient length also are costly and are more difficult to install.
The cross-section of a steel T-post is in the shape of the letter T, and the cross section is designed so that the post will withstand bending moments applied by livestock that may lean or push against the fence. These applied moments are largest near the ground level of a post and decrease with distance upward along the post. A T-post has a cross-section along its length that is approximately uniform, and thus its moment restraint capability is approximately constant along its length. In a long steel T-post, this is wasteful of steel because applied moments in the upper part of the post are much less than the moment restraint capability there.
T-posts longer than about 7.5 ft (2.29 m) will not fit crosswise in most ocean-going containers. Thus, long posts can have a shipping disadvantage.
In many situations, fence supported by T-posts is already in place. To increase its height requires either the replacement of the existing T-posts with longer ones or the addition of longer posts as well as the installation of additional fence material.
Objectives and Advantages of the T-Post Extender and T-Post Combination
For existing T-post supported fence, the T-post extenders of this specification are added to the existing posts thereby increasing their support heights. The T-post extenders are simply slipped into place, and the additional fence is tied or wired on for the required fence height. This is a fast and low cost way to increase the fence height.
Where new fence is required, T-posts of manageable length are driven into the ground, and fence is tied or wired to the posts. Then T-post extenders are slipped onto the T-posts, the combinations thus forming high fence supports. Additional fence is tied or wired on to the high fence supports to obtain the required fence height. In some cases, the T-post extenders are installed first to form the high fence supports before installing any fence. The T-post extenders use less steel than the additional steel that would have been required had longer steel T-posts been purchased. Hence, the high fence support combination of a T-post extender plus a T-post can be less than the cost of a longer T-post.
Both T-posts for use with extenders and T-post extenders may be shipped either crosswise or lengthwise in an ocean-going container. Hence, there is a shipping advantage.
The idea for the present specification came as a result of the following experience. The inventor fenced an area of about 4 acres (1.6 hectares) around his home to keep deer out of a garden and away from landscape plantings. The fence comprised 8-ft (2.44 m) steel T-posts for supports, 47 inch (1.19 m) woven wire and three strands of barbed wire spaced above the woven wire to give a fence height of about 6 ft (1.83 m). The T-posts were easily driven to a depth below ground of about 18 inch (0.46 m) using a hand-operated T-post driver. For a short time, this fence kept the deer out. However, they soon learned the fence could be jumped, and deer were frequently seen inside the fenced area.
It was discovered that a 4-ft (1.22 m) length of ½ inch (13 mm) diameter steel reinforcing bar (rebar), manufactured for concrete reinforcing and left over from a building project, would fit alongside a vertical T-post and be captured laterally by wire ties that attached the existing fence wire to the T-post. A ½ inch steel flat washer, when fitted over the rebar and welded into position about 18 inch (0.46 m) from its lower end, rested on top of the T-post and prevented the rebar from sliding further downward along the T-post. This left about 30 inch (0.76 m) of the rebar extending upward from the top of the T-post, thereby extending the effective height of the T-post by that amount. The rebar with welded on washer became an example of a T-post extender, and in combination with a T-post, became a high fence support.
A T-post extender was inserted at the top of each of the existing T-posts, and an angle iron height extender was bolted on each of the wood corner posts and posts at gate ends to extend their heights. Two additional barb wires were wired onto the T-post extenders giving a total fence height of about 8 ft (2.44 m). The T-post extenders as described allow additional barb wires to be added if necessary to a height of about 9 ft (2.74 m). It has been found that deer are reluctant to jump the 8-ft fence. However, they can jump it, as seen on occasion when a gate is left open. Deer come through the open gate, and in the process of being chased out, they will jump the fence.
On rare occasions, deer will force their way between fence wires. This can be prevented with additional, more closely spaced wires or by using a second tier of 47 inch (1.19 m) woven wire fence tied to the upper parts of the high fence supports.
Summary of Advantages of T-Posts and T-Post Extenders for High Fence Supports.
    Height of existing T-post supported fence may be increased easily.    For existing T-post supported fence, adding T-post extenders is the least costly way to increase fence height.    New high fence is most easily constructed by using T-post extenders with manageable length T-posts and is less costly than alternatives.    This type of high fence support is less wasteful of materials than alternatives.    T-posts with T-post extenders have shipping advantages.